As the number of wireless devices for voice or data increases, mobile data communication will likely emerge as the technology supporting most communication including voice and video. Mobile data communication will be pervasive in cellular systems such as 3G and in wireless LAN such as 802.11, and will extend into satellite communication.
In IP (Internet Protocol) networks, routing is based on stationary IP addresses, similar to how a postal letter is delivered to the fixed address on the envelope. A device on a network is reachable through normal IP routing by the IP address it is assigned on the network.
When a device roams away from its home network it is no longer reachable using normal IP routing. This results in the active sessions of the device being terminated. Mobile protocols (such as the Hierarchical Mobile Internet protocol (HMIP v4 and v6) or the Mobile IP defined by the Internet Engineering Task Force (IETF) RFC 2002) were created to enable users to keep the same IP address while traveling to a different network (which may even be on a different wireless system), thus ensuring that a roaming individual could continue communication without sessions or connections being dropped. When the mobility functions of mobile protocols are performed at the network layer rather than the physical layer, the mobile device can span different types of wireless and wire-line networks while maintaining connections and ongoing applications. In some applications, such as remote login, remote printing, and file transfers, it is undesirable to interrupt communications while an individual roams across network boundaries. Also, certain network services, such as software licenses and access privileges, are based on IP addresses. Changing these IP addresses could compromise the network services.
The concept of local mobility management is well known in the cellular and IP domains. For instance, in a mobile IP network, the concept of a mobility anchor point (MAP) is defined to support fast mobility. A MAP is a node that enhances handoff performance by acting as a care-of-address (CoA) of the mobile node. Specifically, the mobile node registers the address in the network of the MAP with its home agent and its correspondent nodes and registers its “real CoA” with the MAP. As long as the MAP is not changed, a mobile node need not update its home agent and correspondent nodes. However, if the MAP fails or gets disconnected, the correspondent nodes cannot send packets to the mobile node and packets in transit will be lost. Additionally, it takes a significant amount of time to identify the problem and recover. Meanwhile, all packets sent will be lost.